1. Field of the Invention
This invention relates to a semiconductor storage device, such as a static RAM (Random Access Memory), dynamic RAM, EPROM (Electrically Programmable Read-Only memory), OTPROM (One Time Programmable Read-Only Memory), masked ROM, or EEPROM (Electrically Erasable Programmable Read-Only Memory) and particularly it relates to a semiconductor storage device suitable for memory card circuit assemblies and also to a method of accessing the same.
2. Description of the Background Art
As is known in the art, in memory cards such as IC cards, the card substrate is provided with a semiconductor storage device. It has been necessary for such semiconductor storage device to store, besides usual processed data, various identification data (memory capacity, type, access speed, card serial number, data of production, stored contents of the card, code number, etc.). Heretofore, among the known methods of storing such identification data have been the following.
(1) To store identification data in part of the memory without increasing the storage capacity of the memory
(2) To extend the storage capacity of the memory to store identification data in the extended portion,
(3) To provide an auxiliary memory besides the main memory, so as to store identification data in the auxiliary memory.
The conventional methods described above, however, have problems pointed out below.
(1) Usually, since the storage area of the memory is used to capacity, it often happens that there is no storage space left for storing identification data. Therefore, the above method (1) is hard to realize.
(2) As in the above (2), when the storage capacity of the memory is extended, the number of address inputs also has to be increased. As a result, the number of signal lines and the number of pins are increased, leading to an increase in the chip size of the semiconductor storage device. Further, an increase in the number of pins raises a problem that interchangeability with the existing standardized semiconductor storage devices is spoiled.
(3) Usually, the amount of identification data ranges from tens to hundreds of bytes. However, such auxiliary memory of small capacity is usually not included in the standards such as 256K bits, 1M bits and 4M bits, it can hardly be mass-produced, leading to an exorbitant price. Therefore, the method which relies on the provision of a separate auxiliary memory as in the above (3) leads to a great increase in cost.